Thursday, October 30, 2008

BHP vs SHP

Brake horsepower is measured at the crankshaft vs shaft horsepower which is the actual amount of power delivered to the propeller. The latter will be less than the former because of friction losses in the transmission and the stern gland. If the powerplant is not correctly aligned, the losses will certainly be greater. As a rule of thumb, shaft horsepower in small craft is usually between 70 and 90 percent of brake horsepower. The Kitty Hawk class aircraft carriers have eight boilers, four geared steam turbines, four shafts and 280,000 shaft horsepower....so what would be the brake horsepower?